US7859207B2 - Method and apparatus for controlling electric motor - Google Patents

Method and apparatus for controlling electric motor Download PDF

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US7859207B2
US7859207B2 US12/185,963 US18596308A US7859207B2 US 7859207 B2 US7859207 B2 US 7859207B2 US 18596308 A US18596308 A US 18596308A US 7859207 B2 US7859207 B2 US 7859207B2
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temperature
capacitor
electric motor
electric
motor
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US20090039813A1 (en
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Yohei Yamada
Hitoshi Fukada
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Toyota Industries Corp
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Toyota Industries Corp
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Priority claimed from JP2008097950A external-priority patent/JP5217579B2/ja
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/34—Arrangements for starting
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
    • H02P29/60—Controlling or determining the temperature of the motor or of the drive
    • H02P29/68—Controlling or determining the temperature of the motor or of the drive based on the temperature of a drive component or a semiconductor component

Definitions

  • the present invention relates to a method and an apparatus for controlling an electric motor using an inverter device.
  • a PWM control inverter device for controlling an electric motor.
  • the inverter device uses a power transistor or an IGBT (insulated gate bipolar transistor) as a control element.
  • the switching speed of the power transistor or the IGBT is higher than the switching speed of a thyristor inverter.
  • the cable (the wire) connecting the inverter device to the electric motor is long, a surge voltage greater than twice the crest value of the output voltage of the inverter is produced between the terminals of the electric motor.
  • the surge voltage may damage a coil of the electric motor or cause insulation breakdown.
  • Japanese Laid-Open Patent Publication No. 6-38543 discloses a control apparatus that suppresses the generation of a surge voltage.
  • the control apparatus includes a reactor connected to the output of an inverter device and a surge voltage suppressing device connected to the reactor and a terminal of an electric motor.
  • the surge voltage suppressing device includes a circuit in which a capacitor and a resistor are connected in series with each other.
  • the inverter device includes an inverter circuit and a smoothing capacitor.
  • the inverter circuit is configured by a combination of a plurality of semiconductor elements.
  • the smoothing capacitor is connected in parallel with a power supply (a battery).
  • the capacitor has a resistance element caused by the resistance of an electrode or depending on characteristics of a dielectric body. Such a resistance element is called “equivalent series resistance (ESR)”.
  • ESR Equivalent series resistance
  • the ESR may be ignored at temperatures ranging from ambient levels to high levels. However, under a low temperature (which is, for example, 0° C. or lower), the ESR increases to a level at which the ESR cannot be ignored.
  • a motor current flowing in the capacitor produces a surge voltage caused by the ESR.
  • some control apparatuses have a map that stores a maximum acceptable motor current value.
  • the maximum acceptable motor current value represents the maximum value of a motor current that can be supplied to the electric motor at each temperature.
  • Such a control apparatus controls an inverter device based on the map.
  • refrigerant compressed by the compressor may liquefy when the vehicle operates in a cold storage warehouse. This increases the torque necessary for compressing the liquefied refrigerant and the torque for starting the electric motor.
  • the maximum acceptable motor current value thus becomes smaller than a value at which the torque necessary for starting the electric motor is produced.
  • the inverter device includes an inverter circuit and a capacitor connected to an input of the inverter circuit.
  • the method includes: setting a maximum acceptable motor current value using a map or an expression representing a relationship between a temperature of the capacitor and a maximum value of the motor current that prevents a component of the inverter device from being damaged by a surge voltage produced by an equivalent series resistance of the capacitor; estimating a rotational position of a rotor of the electric motor and controlling the inverter circuit in such a manner as to supply a direct electric current smaller than the maximum acceptable motor current value to the electric motor as a d-axis electric current if the temperature of the capacitor is in a range in which the maximum acceptable motor current value is smaller than a value at which a torque necessary for starting the electric motor is produced; and controlling the inverter circuit in such a manner as to supply an alternating electric current to the electric motor after the temperature of the capacitor reaches a temperature at which the maximum acceptable motor current value becomes greater than or equal to the value at which the torque necessary for starting the electric motor is produced.
  • an apparatus for adjusting a motor current supplied to an electric motor using an inverter device includes an inverter circuit and a capacitor connected to an input of the inverter circuit.
  • the apparatus includes a temperature detecting section, a memory section, a rotor position estimating section, a maximum acceptable motor current value calculating section, and an inverter device control section.
  • the temperature detecting section detects a temperature of the capacitor or a temperature reflecting the temperature of the capacitor.
  • the memory section stores a map or an expression representing a relationship between a maximum acceptable motor current value and the temperature of the capacitor.
  • the maximum acceptable motor current value is a maximum value of the motor current that prevents a component of the inverter device from being damaged by a surge voltage produced by an equivalent series resistance of the capacitor.
  • the rotor position estimating section estimates a rotational position of a rotor of the electric motor.
  • the maximum acceptable motor current value calculating section calculates the maximum acceptable motor current value corresponding to the temperature of the capacitor based on a temperature detected by the temperature detecting section and either of the map or the expression.
  • the inverter device control section controls the inverter circuit in such a manner as to supply a direct electric current smaller than the maximum acceptable motor current value to the electric motor as a d-axis electric current based on the rotational position of the rotor estimated by the rotor position estimating section and the maximum acceptable motor current value calculated by the maximum acceptable motor current value calculating section.
  • FIG. 1 is a diagram showing a control apparatus according to a first embodiment of the present invention
  • FIG. 2 is a block diagram representing a procedure of calculation performed by the control apparatus shown in FIG. 1 ;
  • FIG. 3 is a diagram representing the relationship among the maximum acceptable motor current value, the capacitor temperature, and the required motor starting current value
  • FIG. 4 is a flowchart representing a preheating control procedure carried out by the control apparatus of FIG. 1 ;
  • FIG. 5 is a graph representing changes of applied voltages of the U, V, and W phases
  • FIG. 6 is a flowchart representing a preheating control procedure performed by a control apparatus according to a second embodiment of the present invention.
  • FIG. 7 is a flowchart representing a preheating control procedure performed by a control apparatus according to a third embodiment of the present invention.
  • FIG. 8 is a graph representing changes over time of an electric current supplied to an electric motor by the control apparatus according to the third embodiment of the invention.
  • FIG. 9 is a graph representing the relationship between the switching time and the electric current flowing in the cable of the U phase according to another embodiment.
  • the control apparatus 11 controls an electric motor 10 for an electric compressor of an air conditioner mounted in a vehicle.
  • the control apparatus 11 of the electric motor 10 has an inverter device 12 and a control section 13 serving as an inverter device control section.
  • the electric motor 10 is a three-phase AC motor.
  • the inverter device 12 is connected to a main battery 14 , or a power supply for driving the vehicle, through a fuse 15 .
  • the inverter device 12 includes an inverter circuit 16 having six switching elements Q 1 , Q 2 , Q 3 , Q 4 , Q 5 , Q 6 .
  • Each of the switching elements Q 1 to Q 6 is an IGBT (insulated gate bipolar transistor).
  • the first switching element Q 1 , the third switching element Q 3 , and the fifth switching element Q 5 are connected in series with the second switching element Q 2 , the fourth switching element Q 4 , and the sixth switching elements Q 6 , respectively.
  • the first, third, and fifth switching elements Q 1 , Q 3 , and Q 5 are connected to the positive terminal of the main battery 14 through a coil 17 and the fuse 15 .
  • the second, fourth, and sixth switching elements Q 2 , Q 4 , and Q 6 are connected to the negative terminal of the main battery 14 .
  • the node between the switching element Q 1 and the switching element Q 2 is connected to the U phase terminal of the electric motor 10 .
  • the node between the switching element Q 3 and the switching element Q 4 is connected to the V phase terminal of the electric motor 10 .
  • the node between the switching element Q 5 and the switching element Q 6 is connected to the W phase terminal of the electric motor 10 .
  • Electric current sensors 18 a , 18 b which are electric current detecting sections, are provided in a cable connecting the inverter device 12 to the electric motor 10 .
  • the electric current sensors 18 a , 18 b detect two of the electric currents Iu, Iv, Iw in the three phases (in the first embodiment, the electric currents of the U and W phases), which are supplied to the electric motor 10 , or the electric currents Iu, Iw.
  • the control apparatus 11 includes a voltage sensor 19 connected to the inverter device 12 .
  • the inverter circuit 16 is connected to a capacitor (an input capacitor) 20 connected in parallel with the main battery 14 .
  • the capacitor 20 of the first embodiment is an electrolytic capacitor.
  • the first, third, and fifth switching elements Q 1 , Q 3 , and Q 5 are connected to the positive terminal of the capacitor 20 .
  • the second, fourth, and sixth switching elements Q 2 , Q 4 , and Q 6 are connected to the negative terminal of the capacitor 20 .
  • FIG. 1 illustrates a resistor Rs connected in series with the capacitor 20 .
  • the resistor Rs represents equivalent series resistance (ESR) of the capacitor 20 .
  • the control apparatus 11 also includes a temperature sensor 21 , or a temperature detecting section detecting a temperature that reflects the temperature of the capacitor 20 .
  • the temperature sensor 21 is connected to the control section 13 .
  • the temperature sensor 21 may be arranged at any suitable position. That is, the position of the temperature sensor 21 is not restricted to a position in the close vicinity of the capacitor 20 . In the first embodiment, the temperature sensor 21 is located in the vicinity of the switching elements.
  • the control section 13 which controls the inverter device 12 , includes a CPU (central processing unit) 22 and a memory 23 serving as a memory section.
  • the memory 23 stores control programs according to which the electric motor 10 is controlled and data and maps needed to perform the control programs.
  • the control programs include a control program according to which the electric motor 10 is subjected to vector control, a control program according to which a maximum acceptable motor current value is calculated for a certain capacitor temperature based on a detection result of the temperature sensor 21 or with reference to a map, and a control program according to which a d-axis direct electric current is supplied to the electric motor 10 .
  • the CPU 22 is connected to a gate, or a control terminal, of each of the switching elements Q 1 to Q 6 through a non-illustrated driver circuit.
  • the CPU 22 is connected to the electric current sensors 18 a , 18 b and the voltage sensor 19 through a non-illustrated input interface.
  • the CPU 22 outputs control signals to each switching element Q 1 to Q 6 through the driver circuit based on detection signals from the sensors 18 a , 18 b , 19 , 21 .
  • the electric motor 10 is controlled in such a manner that the output of the electric motor 10 reaches a target output value.
  • the inverter circuit 16 inverts a direct current voltage supplied from the main battery 14 to a three phase alternating voltage having an appropriate frequency and outputs the alternating voltage to the electric motor 10 .
  • the control section 13 performs calculation in accordance with the procedure represented in FIG. 2 .
  • the control section 13 includes a capacitor temperature calculating section 24 , a maximum acceptable motor current value calculating section 25 , a rotor phase estimating section (a rotor position estimating section) 26 , a target d-axis motor current value calculating section 27 , and a command voltage calculating section 28 .
  • the capacitor temperature calculating section 24 estimates the capacitor temperature in correspondence with the detection signal of the temperature sensor 21 .
  • the maximum acceptable motor current value calculating section 25 calculates the maximum acceptable motor current value for the capacitor temperature obtained by the capacitor temperature calculating section 24 with reference to the map.
  • the rotor phase estimating section 26 estimates the rotational position (the rotational phase ⁇ ) of the rotor based on the output signals of the electric current sensors 18 a , 18 b and the voltage sensor 19 .
  • the rotational position of the rotor is estimated, for example, in the following manner. That is, a voltage pulse is calculated from the voltage detected by the voltage sensor 19 . The voltage pulse is then applied to the U, V, and W phases of the electric motor 10 and the amount of the electric current flowing in each of the phases is detected by the corresponding one of the electric current sensors 18 a , 18 b .
  • the rotational position of the rotor is then estimated through comparison between the detection signals of the electric current sensors 18 a , 18 b and a rotor position estimation map stored in the memory 23 .
  • the target d-axis motor current value calculating section 27 sets a target d-axis motor current value using the maximum acceptable motor current value obtained by the maximum acceptable motor current value calculating section 25 and the phase ⁇ determined by the rotor phase estimating section 26 .
  • the command voltage calculating section 28 calculates a command voltage that is to be supplied to the electric motor 10 . In other words, the command voltage calculating section 28 converts a command d-axis electric current and a command q-axis electric current to a corresponding command two-phase voltage. The command two-phase voltage is then converted to a command three-phase voltage corresponding to the U, V, and W phases through a non-illustrated two phase/three phase converting section. Eventually, the command three-phase voltage is output to the electric motor 10 .
  • control apparatus 11 Operation of the control apparatus 11 will hereafter be explained with reference to the flowchart represented in FIG. 4 .
  • the CPU 22 After the control apparatus 11 is started, the CPU 22 first receives a detection signal from the temperature sensor 21 and calculates the capacitor temperature (step S 1 ). The CPU 22 then determines the maximum acceptable motor current value corresponding to the capacitor temperature with reference to a map representing the relationship between the capacitor temperature and the maximum acceptable motor current value. Also, the CPU 22 determines whether the maximum acceptable motor current value is smaller than a value at which the torque necessary for starting the electric motor 10 is generated (step S 2 ). With reference to FIG. 3 , the map stores the relationship among the capacitor temperature, the maximum acceptable motor current value, and the electric current value required for producing the torque necessary for starting the electric motor 10 . In the first embodiment, the maximum acceptable motor current is supplied at 0° C. or more, with reference to FIG. 3 . However, the maximum acceptable motor current may be supplied at a temperature lower than 0° C., depending on the type of the capacitor employed.
  • the CPU 22 performs normal control if, in step S 2 , the capacitor temperature is in a range in which the maximum acceptable motor current value is greater than or equal to a value at which the torque necessary for starting the electric motor 10 is produced (step S 3 ).
  • the switching elements Q 1 to Q 6 are controlled in such a manner that the d-axis electric current and the q-axis electric current are smaller than the maximum acceptable motor current value and that the output of the electric motor 10 achieves a target speed and a target torque.
  • step S 2 If determination of step S 2 is positive, that is, if the capacitor temperature is in a range in which the maximum acceptable motor current value is smaller than the value at which the torque necessary for starting the electric motor 10 is produced, the CPU 22 supplies an electric current to the capacitor 20 and performs preheating control.
  • the CPU 22 calculates the maximum acceptable motor current value corresponding to the current capacitor temperature (step S 4 ).
  • the CPU 22 estimates the rotational position (the phase ⁇ ) of the rotor in correspondence with the detection signals of the electric current sensors 18 a , 18 b and the voltage sensor 19 (step S 5 ). Subsequently, the CPU 22 determines the target d-axis electric current using the calculated maximum acceptable motor current value and the determined phase ⁇ (step S 6 ).
  • the CPU 22 determines the command d-axis voltage value and the command q-axis voltage value, and outputs a control signal in correspondence with which the d-axis motor current value and the d-axis motor current value reach the target d-axis electric current value and the target q-axis electric current value (0[A]), respectively, to the inverter circuit 16 (step S 7 ).
  • the switching elements Q 1 to Q 6 are then selectively switched on and off by the duty cycle corresponding to the control signal.
  • the target q-axis electric current value is adjusted to 0[A]. This provides a direct electric current corresponding to the target d-axis electric current value to the electric motor 10 .
  • the switching elements Q 1 to Q 6 are selectively switched on and off in such a manner that the direct electric current is supplied also to the capacitor 20 .
  • Such supply of the direct electric current to the capacitor 20 heats the capacitor 20 .
  • the procedure corresponding to steps S 1 to S 7 is repeatedly carried out until the capacitor temperature reaches a temperature at which the maximum acceptable motor current value is greater than or equal to the value at which the torque necessary for starting the electric motor 10 is produced.
  • the CPU 22 ends the preheating control and switches to the normal control.
  • the maximum value of the electric current supplied to the respective one of the U, V, and W phases is determined in correspondence with the maximum acceptable motor current value and the position of the rotor at the current point in time.
  • the CPU 22 controls the voltage supplied to each of the U, V, and W phases in such a manner that the electric current flowing in each of the U, V, and W phases gradually reaches the target electric current value, instead of controlling the voltage supply in such a manner that the target d-axis electric current is supplied to the U, V, and W phases from the start.
  • the first embodiment has the following advantages.
  • the control apparatus 11 includes the temperature sensor 21 , which detects the temperature the capacitor 20 connected to the input of the inverter circuit 16 or a temperature reflecting the capacitor temperature, and the map representing the relationship between the temperature of the capacitor 20 and the maximum acceptable motor current value, which prevents a component of the inverter device 12 from being damaged by a surge voltage produced by an equivalent series resistance of the capacitor 20 .
  • the control apparatus 11 controls the inverter circuit 16 in such a manner that an electric current smaller than the maximum acceptable motor current value flows in the electric motor 10 , using the map. In this manner, the components of the inverter device 12 are prevented from being damaged by the surge voltage under a low temperature.
  • the control apparatus 11 has the maximum acceptable motor current value calculating section 25 , which calculates the maximum acceptable motor current value based on the map.
  • the control apparatus 11 further includes the control section 13 , which controls the inverter device 12 in such a manner that a direct electric current smaller than the maximum acceptable motor current value is supplied to the electric motor 10 as a d-axis electric current based on the position of the rotor estimated from the detection signals of the electric current sensors 18 a , 18 b and the voltage sensor 19 and the maximum acceptable motor current value calculated by the maximum acceptable motor current value calculating section 25 .
  • the control apparatus 11 performs the preheating control. Specifically, the control apparatus 11 supplies a d-axis electric current smaller than the maximum acceptable motor current value to the capacitor 20 , thus heating the capacitor 20 . The control apparatus 11 then provides an alternating electric current to the electric motor 10 to start the electric motor 10 .
  • the capacitor temperature is in the range in which the maximum acceptable motor current value is smaller than the value at which the torque necessary for starting the electric motor 10 is generated, that is, if the ambient temperature (the temperature in the environment) of the control apparatus 11 is low, the torque required for starting the electric motor 10 is produced while an excessively great surge voltage is prevented from being generated.
  • the position of the rotor is estimated based on the detection signals of the electric current sensors 18 a , 18 b and the voltage sensor 19 . This makes it unnecessary to provide an additional sensor for estimation of the rotational position of the rotor of the electric motor 10 .
  • the switching elements Q 1 to Q 6 are selectively switched on and off in such a manner that the electric current supplied to the electric motor 10 gradually increases to the target electric current value (the maximum acceptable motor current value), instead of operating the switching elements Q 1 o Q 6 in such a manner that the target d-axis electric current is supplied to the electric motor 10 from the start. This decreases an overshoot current and suppresses noise.
  • the electric motor 10 is an electric motor for an electric compressor. If the electric compressor is driven at a low temperature (which is, for example, 0° C. or lower), the refrigerant compressed by the compressor liquefies and increases the torque necessary for driving the electric motor 10 . Thus, without the preheating control, the range of the temperature that allows the electric motor 10 to be actuated at a low temperature is limited. However, through the preheating control, such range is enlarged. The electric motor 10 is thus desirable for use as the electric motor for an electric compressor.
  • a second embodiment of the present invention will hereafter be described with reference to FIG. 6 .
  • the second embodiment employs a method for calculating the capacitor temperature different from that of the first embodiment. Same or like reference numerals are given to components of the second embodiment that are the same as or like corresponding components of the first embodiment and explanation thereof is omitted.
  • the CPU 22 receives the current detection signal of the temperature sensor 21 and calculates the capacitor temperature. However, in the second embodiment, the CPU 22 calculates the capacitor temperature based on the detection signal of the temperature sensor 21 restrictedly when the inverter device 12 is started. Afterwards, the capacitor temperature when the inverter device 12 is started is employed as a reference temperature. The CPU 22 thus estimates (calculates) the capacitor temperature based on the reference temperature, the amount of the electric current supplied to the inverter device 12 , and the duration of such electric current supply.
  • the memory 23 stores the reference temperature, and a map or an expression using which the capacitor temperature after starting of the control apparatus 11 is calculated based on the amount of the electric current supplied to the inverter device 12 and the duration of such electric current supply.
  • the map is created in advance through a simulation or actual operation of the electric motor 10 . Further, the CPU 22 consecutively calculates the amount of the electric current supplied to the inverter device 12 and the duration of such electric current supply and stores the results in the memory 23 .
  • control apparatus 11 performs the same procedure as that of the first embodiment except for steps corresponding to step S 1 .
  • steps S 2 to S 7 of FIG. 4 are omitted.
  • the control apparatus 11 sequentially carries out step S 1 a , step S 1 b , and step S 1 c , instead of step S 1 .
  • step S 7 of the flowchart of FIG. 4 the control apparatus 11 returns to step S 1 c instead of step S 1 .
  • the CPU 22 receives the detection signal of the temperature sensor 21 (step S 1 a ).
  • the CPU 22 determines the capacitor temperature, sets the capacitor temperature to the reference temperature, and stores the reference temperature in the memory 23 (step S 1 b ).
  • the CPU 22 determines the capacitor temperature after starting of the control apparatus 11 in correspondence with the reference temperature, the amount of the electric current supplied by the current point in time, and the duration of such electric current supply, using the map (step S 1 c ).
  • the CPU 22 then performs steps S 2 to S 7 as in the first embodiment. After step S 7 , the CPU 22 returns to step S 1 c .
  • the second embodiment is different from the first embodiment in that reception of the detection signal from the temperature sensor 21 by the CPU 22 occurs restrictedly when the control apparatus 11 is started.
  • the CPU 22 calculates the capacitor temperature in correspondence with the reference temperature, the amount of the electric supplied by the current point in time, and the duration of such electric current supply using the map, without receiving the detection signal of the temperature sensor 21 , not only in the preheating control but also after the control by the CPU 22 is switched to the normal control.
  • the second embodiment has the following advantage in addition to the advantages equivalent to those described in (1) to (5) of the first embodiment.
  • the maximum acceptable motor current value corresponding to the calculated capacitor temperature is determined in correspondence with the reference temperature, the amount of the electric current supplied by the current point in time, and the duration of such electric current supply, using the map.
  • the temperature of each portion of the inverter device 12 dose not become equivalent to the capacitor temperature or change in proportion to the capacitor temperature while the capacitor temperature is raised through warm-up of the electric motor 10 .
  • the temperatures of the portions spaced from the capacitor 20 do not reflect the capacitor temperature.
  • the temperature sensor 21 is located at a position at which the local temperature does not reflect the actual temperature of the capacitor 20 , the increase amount of the capacitor temperature becomes extremely small, despite the fact that the actual temperature of the capacitor 20 rises as the time elapses since starting of the electric motor 10 . This decreases the amount of the d-axis electric current supplied in the preheating control.
  • the capacitor temperature when the inverter device 12 is started obtained by the temperature sensor 21 is employed as the reference temperature.
  • the temperature of the capacitor 20 is estimated in correspondence with the reference temperature, the amount of the electric current supplied to the inverter device 12 , and the duration of such electric current supply. Accordingly, regardless of the position at which the temperature sensor 21 is deployed, the temperature of the capacitor 20 is estimated accurately. Thus, a limited electric current corresponding to the actual temperature of the capacitor 20 is provided as the d-axis electric current. As a result, the warm-up of the electric motor 10 is completed quickly.
  • the temperature sensor 21 is arranged at the position at which increase of the temperature of the capacitor 20 is not reflected at a low ambient temperature (for example, 0° C. or lower), it is unnecessary to employ an additional sensor that directly detects the temperature of the capacitor 20 .
  • a third embodiment of the present invention will hereafter be explained with reference to FIGS. 7 and 8 .
  • the third embodiment employs conditions different from those of the first embodiment when the preheating control is switched to the normal control. Same or like reference numerals are given to components of the third embodiment that are the same as or like corresponding components of the first embodiment and explanation thereof is omitted.
  • the normal control is carried out if the capacitor temperature reaches the range in which the maximum acceptable motor current value is greater than or equal to the value at which the torque necessary for starting the electric motor 10 is produced.
  • the q-axis electric current is supplied to the electric motor 10 with the motor output being limited, and a surplus electric current that can be supplied under such output limitation is fed to the electric motor 10 as the d-axis electric current, until the capacitor temperature reaches a value at which the output limitation becomes unnecessary. After the capacitor temperature reaches the value, the normal control is performed.
  • control apparatus 11 of the third embodiment is different from that of the first embodiment in that steps S 8 , S 9 , S 10 are carried out instead of step S 3 of the first embodiment.
  • step S 2 determines whether the capacitor temperature is lower than a temperature at which output limitation is unnecessary (step S 8 ). If negative determination is made in step S 8 , or the capacitor temperature is greater than or equal to the temperature at which the output limitation is unnecessary, the CPU 22 carries out the normal control (step S 10 ).
  • step S 8 determines whether the capacitor temperature is less than the value at which the output limitation is unnecessary. If determination of step S 8 is positive, that is, if the capacitor temperature is less than the value at which the output limitation is unnecessary, the CPU 22 operates the electric motor 10 at a low speed (step S 9 ). In other words, when the electric motor 10 is rotated at a low speed, the capacitor temperature is less than a value at which the maximum acceptable motor current value can be supplied, or the value at which the output limitation is unnecessary.
  • the CPU 22 controls the electric motor 10 in such a manner that the output of the electric motor 10 becomes close to the torque required by a load without exceeding the maximum acceptable motor current value corresponding to the capacitor temperature.
  • the CPU 22 controls the inverter device 12 in such a manner that the electric current value increases sequentially at regular time intervals, as illustrated in FIG. 8 , instead of supplying the electric current corresponding to the required torque to the electric motor 10 from the start.
  • the q-axis electric current is set to the value corresponding to the current electric current value at each point of time of FIG. 8 .
  • the d-axis electric current is set to a maximum electric current value not exceeding the limitation value at the current temperature.
  • the third embodiment has the following advantage in addition to the advantages equivalent to (1) to (5) of the first embodiment.
  • the q-axis electric current is supplied and an electric current is fed by an amount permitted under such limitation until the capacitor temperature reaches the value at which the output limitation is necessary. This shortens the period of time until the capacitor temperature reaches the value at which the output limitation is necessary.
  • the electric motor 10 is allowed to operate in correspondence with a great required torque at an early stage.
  • the position of the rotor may be estimated in the following manner. Specifically, a constant electric current is supplied to the cable of each of the U, V, and W phases of the electric motor 10 . The voltage of each of the cables is detected by a voltage sensor. The position of the rotor is estimated based on a detection signal of the voltage sensor. In this case, a voltage sensor that detects the voltages of the cables of at least two of the U, V, and W phases is provided.
  • a rotor position sensor 30 which is included in the rotor phase estimating section, may be provided in the electric motor 10 to detect the position of the rotor as shown by a dashed line in FIG. 1 .
  • the rotor position sensor 30 may be, for example, a rotary encoder or a resolver.
  • the switching frequency of the switching elements Q 1 to Q 6 in the preheating control of the capacitor 20 may be higher than the switching frequency of the switching elements Q 1 to Q 6 in the normal control. This shortens the cycle at which the electric current flows to and from the capacitor 20 , thus raising the temperature of the capacitor 20 quickly.
  • the switching frequency in the normal control is not more than several hundreds of microseconds.
  • the on-duty of the switching elements Q 1 to Q 6 may be gradually decreased so that the amount of the electric current flowing in each of the U, V, and W phases increases.
  • FIG. 6 represents changes of the electric current flowing in the cable of the U phase. This further decreases an overshoot electric current.
  • the capacitor temperature rises to the range in which the maximum acceptable motor current value is greater than or equal to the value at which the torque necessary for starting the electric motor 10 is produced.
  • the electric motor 10 may be operated with a lower target torque for a predetermined time before the target torque is raised. In this case, the electric motor 10 is operated stably compared to the case in which the electric motor 10 is operated with the raised target torque from the start.
  • Supply of an alternating electric current to the electric motor 10 which is to start the electric motor 10 , does not necessarily have to be started immediately after the temperature of the capacitor 20 reaches the temperature at which the corresponding maximum acceptable motor current value produces the torque necessary for starting the electric motor 10 .
  • the electric motor 10 may be started after the temperature of the capacitor 20 increases to 0° C. or higher.
  • the capacitor temperature is calculated from the detection signal of the temperature sensor 21 at each reception of the signal.
  • calculation of the capacitor temperature may be performed only when the control apparatus 11 is started. Afterwards, the capacitor temperature is calculated in correspondence with the reference temperature, the amount of the electric current supplied by the current point in time, and the duration of such current supply using the map.
  • the capacitor temperature when the inverter device 12 is started is employed as the reference temperature.
  • the capacitor temperature is calculated based on the reference temperature, the amount of the electric current supplied to the inverter device 12 , and the duration of such current supply.
  • such method of calculation may be employed only in the preheating control. In this case, after the capacitor temperature rises sufficiently high exceeding, for example, 0° C., the temperature of the capacitor 20 may be calculated based on the detection signal of the temperature sensor 21 .
  • the memory 23 may store an expression representing the relationship between the maximum acceptable motor current value and the capacitor temperature, instead of the map representing such relationship.
  • the maximum acceptable motor current value is calculated using the expression.
  • the electric motor 10 If the electric motor 10 is driven through the inverter device 12 , the electric motor constant changes depending on the electric motor specification. This correspondingly changes the capacitor temperature and the motor current limitation map according to which the inverter device 12 is optimally controlled and commanded.
  • management load of software increases. Also, erroneous writing of the software may occur.
  • the necessary information is to be provided as a mask ROM instead of the software, a large number of types of mask ROMs must be provided, which may lead to erroneous installment.
  • information necessary for calculation of the outputs of the electric motors of different specifications may be provided as maps included in software.
  • the type of the electric motor is specified using a switch or a pull-up/pull-down resistor external to the ROM.
  • a switch or a pull-up/pull-down resistor external to the ROM only one type of software is necessary, and the management load of the software decreases. Also, erroneous writing of the software is prevented. If a bug occurs in a basic software portion, the problem is solved only by changing the single software. If the information is provided as the mask ROM, the switching cost due to bugs or the like is advantageously reduced.
  • the switching elements Q 1 to Q 6 may be MOSFETs or bipolar transistors.
  • the electric motor 10 is not restricted to an electric motor for an electric compressor.
  • the electric motor 10 may be any suitable type, as long as the electric motor is controlled through an inverter and used under low temperature.
  • the electric motor 10 may be an electric motor used in a vehicle or an electric motor for a machining tool. If the electric motor 10 is the electric motor for the vehicle, the electric motor 10 effectively functions at a temperature below the freezing point.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)
  • Control Of Ac Motors In General (AREA)
  • Motor And Converter Starters (AREA)
US12/185,963 2007-08-06 2008-08-05 Method and apparatus for controlling electric motor Active 2029-07-24 US7859207B2 (en)

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JP2007-204522 2007-08-06
JP2007204522 2007-08-06
JP2008097950A JP5217579B2 (ja) 2007-08-06 2008-04-04 電動機の制御方法及び制御装置
JP2008-097950 2008-04-04

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US20090289586A1 (en) * 2008-05-22 2009-11-26 Denso Corporation Apparatus for estimating rotor position of brushless motors and system and method for controlling start-up of brushless motors
US20090289587A1 (en) * 2008-05-22 2009-11-26 Denso Corporation Apparatus for estimating rotor position of brushless motors and system and method for controlling start-up of brushless motors
US20120086371A1 (en) * 2010-10-08 2012-04-12 Denso Corporation Rotary electric machine for vehicles
US20130020971A1 (en) * 2011-07-22 2013-01-24 GM Global Technology Operations LLC Temperature compensation for improved field weakening accuracy
US20130320747A1 (en) * 2011-02-25 2013-12-05 Takayoshi Ozaki Electric automobile
US20140015461A1 (en) * 2012-07-12 2014-01-16 Kabushiki Kaisha Toyota Jidoshokki Inverter
US20150318813A1 (en) * 2013-01-21 2015-11-05 Trane International Inc. Refrigerant compressor drives offering enhanced robustness, efficiency and rated voltage operability
US9577510B2 (en) 2012-11-26 2017-02-21 Kabushiki Kaisha Toyota Jidoshokki Inverter device
US9825615B2 (en) 2012-07-05 2017-11-21 Hanon Systems Method for operating an inverter of an electrical refrigerant compressor making use of DC link electrolyte capacitors
US9981529B2 (en) 2011-10-21 2018-05-29 Honeywell International Inc. Actuator having a test mode
US10128788B2 (en) 2016-01-28 2018-11-13 Trane International Inc. Increasing component life in a variable speed drive with stator heating
US20220200482A1 (en) * 2019-05-07 2022-06-23 Sanden Automotive Components Corporation Inverter device

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JP5925425B2 (ja) * 2011-04-07 2016-05-25 サンデンホールディングス株式会社 インバータ装置
GB2503671B (en) * 2012-07-03 2014-12-17 Dyson Technology Ltd Control of a brushless motor
GB2503670B (en) 2012-07-03 2014-12-10 Dyson Technology Ltd Method of preheating a brushless motor
DE102012213908A1 (de) * 2012-08-06 2014-02-06 Robert Bosch Gmbh Steuereinheit für eine elektrische Maschine
JP6024601B2 (ja) 2012-11-26 2016-11-16 株式会社豊田自動織機 インバータの暖機制御装置
US9106171B2 (en) * 2013-05-17 2015-08-11 Honeywell International Inc. Power supply compensation for an actuator
JP5975017B2 (ja) 2013-12-05 2016-08-23 株式会社豊田自動織機 電動圧縮機
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JP2016082685A (ja) * 2014-10-15 2016-05-16 本田技研工業株式会社 ブラシレスモータ及び電動パワーステアリング装置
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US20090289587A1 (en) * 2008-05-22 2009-11-26 Denso Corporation Apparatus for estimating rotor position of brushless motors and system and method for controlling start-up of brushless motors
US8054017B2 (en) * 2008-05-22 2011-11-08 Denso Corporation Apparatus for estimating rotor position of brushless motors and system and method for controlling start-up of brushless motors
US8072165B2 (en) * 2008-05-22 2011-12-06 Denso Corporation Apparatus for estimating rotor position of brushless motors and system and method for controlling start-up of brushless motors
US20090289586A1 (en) * 2008-05-22 2009-11-26 Denso Corporation Apparatus for estimating rotor position of brushless motors and system and method for controlling start-up of brushless motors
US8716966B2 (en) * 2010-10-08 2014-05-06 Denso Corporation Rotary electric machine for vehicles
US20120086371A1 (en) * 2010-10-08 2012-04-12 Denso Corporation Rotary electric machine for vehicles
US9751409B2 (en) 2011-02-25 2017-09-05 Ntn Corporation Electric automobile
US8950528B2 (en) * 2011-02-25 2015-02-10 Ntn Corporation Electric automobile
US20130320747A1 (en) * 2011-02-25 2013-12-05 Takayoshi Ozaki Electric automobile
US20130020971A1 (en) * 2011-07-22 2013-01-24 GM Global Technology Operations LLC Temperature compensation for improved field weakening accuracy
US8519648B2 (en) * 2011-07-22 2013-08-27 GM Global Technology Operations LLC Temperature compensation for improved field weakening accuracy
US10744848B2 (en) * 2011-10-21 2020-08-18 Honeywell International Inc. Actuator having a test mode
US20180251010A1 (en) * 2011-10-21 2018-09-06 Honeywell International Inc. Actuator having a test mode
US9981529B2 (en) 2011-10-21 2018-05-29 Honeywell International Inc. Actuator having a test mode
US9825615B2 (en) 2012-07-05 2017-11-21 Hanon Systems Method for operating an inverter of an electrical refrigerant compressor making use of DC link electrolyte capacitors
US9048771B2 (en) * 2012-07-12 2015-06-02 Kabushiki Kaisha Toyota Jidoshokki Inverter
US20140015461A1 (en) * 2012-07-12 2014-01-16 Kabushiki Kaisha Toyota Jidoshokki Inverter
US9577510B2 (en) 2012-11-26 2017-02-21 Kabushiki Kaisha Toyota Jidoshokki Inverter device
US9595905B2 (en) * 2013-01-21 2017-03-14 Trane International Inc. Refrigerant compressor drives offering enhanced robustness, efficiency and rated voltage operability
US20150318813A1 (en) * 2013-01-21 2015-11-05 Trane International Inc. Refrigerant compressor drives offering enhanced robustness, efficiency and rated voltage operability
US10128788B2 (en) 2016-01-28 2018-11-13 Trane International Inc. Increasing component life in a variable speed drive with stator heating
US20220200482A1 (en) * 2019-05-07 2022-06-23 Sanden Automotive Components Corporation Inverter device
US11750113B2 (en) * 2019-05-07 2023-09-05 Sanden Corporation Inverter device

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EP2028759A3 (fr) 2013-12-25
EP2028759B1 (fr) 2014-12-17
EP2028759A2 (fr) 2009-02-25

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